Lock-out party-line telephone system.



I B. I). WILLIS. LOCK-OUT PARTYQLLNE TELEPHONE SYSTEM.

191669645. APPLICATION FILED m. 29, 1912. Patented (fan. 4 1916.

2 SHEETS-SHEET I.

Y B. D. WILLIS-I I LOCK-OUT PARTY LINE TELEPHONE SYSTEM.

APPLICATLON FILED FEB.'29I 1912. 1,166,645.

2 SHEETS-SHEET 2.

Patented an. 4, 1916.

I To all whom itmag concern BER-Nani) :5. warns, on CHICAGO, ILLINoIs,AssIs'Non .TO AUTOMATIC ELECTRIC COMPANY, or CHICAGO, ILLINOIS, aoonron-ATIoN or ILLINOIS.

Loon-our" renter-LINE TELEPHONE I sYsrEM.

' Specification of Letters Patent;

racemes Jan. 4, 1916.

Be it known that "I, BERNARD D. WILLIS, a citizen of the UnitedStates'of America, and resident of Chicago, in the county of Cook andState of Illinois, have invented certain new and useful Improvements inLock-Out Party Line Telephone Systems,

of which the following is a specification.

My invention relates .to' party-linetelephone systems, and moreparticularly to an improved lock-out device by which means are providedscriber from coming in upon ths line when one subscriber upon the lineis using the sam e,' iv

invention isparticul'arly adapted tor. use Iii-connection with automaticor semiautomatic "telephone' systems in which 'an automatic callingdevice is provided at "the subscribers stations.

Among the specific objects of my inventionare to provide a relay'which,upon'ener- Y s z g,

line. This relay is marginal in operation, I

bridges the talking circuit across the and-lwill not energize if thetalking circuit of any vother substation isj bridged across the'line.'Incombination with this relayl provide an' electromagnet which isenergized :when the subscriber replaces his re'-.

ceiver upon the hook, which magnet oper= atesto return the operatedparts to their normal positions. These and other ob ects -of.myinvention will be more readily and' clearly understood by re,ference tothe accompanying drawings, inwhich-'- Figures 1 and 2 taken togethershow a complete connection between a calling substation A and a' calledsubstation A in a telephone system embodying the principles of myinvention.

The telephone system v automatic system of the shown herei'n'is anwell-known type in which the connections are established between-thecalling and called lines through there is shown a the medium ofindividual preselector or line switches," first and second selectorswitches and connectors The connection shown" is established through themedium of first selector E, second selector F and the connector H. At Dthere is shown the usual master switch for controlling the line switchC. At B (Fig, 2) central ofiice battery for supplying current foroperating the switches and "for talking purposes.

for preventing a second sub difierent stations on the same line inay be'trate my invention and as shown at Fl 1 comprise the usual receiver 2,trans- At R a ringing signaled selectively: Very satisfactory resultsare obtained by the following wellknown arrangement, in which the bellsof the difierent substations are tuned or otherwise adapted to respondto only a certain. kind of ringing'curr'ent. oflice means are providedfor producing as many different kinds of ringing current as there aresubstations upon each line. Each line is accessible through as manydifie'rent groups of connector switches as there are substations on it,and each group of connectors is supplied with ringing current of adifferent character. Thus, to-signal any At the central. j

particular substation on a line it is neces-- sary to call this linethrough the medium,

'ofa connector in a group which is supplied with ringing current of theproper character to operate the bells atthe substation desired. Each ofthe different groups of connectors which have access to the same linemaybe accessible through a difierentlevel of the second selectors, so thatthe numbers of the different substations on each line may be different,and the proper group of connectors will be automatically selected whenthe number of any substation is called.

The substations may be of any suitable common battery twowire automatictype. The ones with which I have elected to illus- P) mitter 3, switchhook 4:, ringer 5 and con denser 6. Being an automatic substation itmust alsobe provided with an. automatic calling device. This callingdevice'may be of the type shown in .British patent to S. G. Dicker, No.29,654: of 1910, but is herein represented diagrammatically by a.

pair of impulse springs 7 and'8 and the toothed impulse wheel 9,wh1chlatter may be controlled by the-subscriber through the medium of adial (not shown), which dial is provided with finger holes in such amanner that it may be operated to cause the springs 7 and 8 to beseparated momentarily a number of times, corresponding to the respectivedigits of the number to be called. WVith each substation there are alsoassociated two relays 10 and 11. These. relays are interlockingthat is,they are so arranged that when the relay 11 becomes energized itscontact springs become locked in their operated positions and cannotreturn to normal position until the relay 10 has been energized. Anysuitable interlocking means may be used in connection with these relays.As shown herein, this means comprises a U-shaped lever 12 which, whenthe relay 11 is energized, drops down behind the armature 13 and willnot permit said armature to restore to its normal position until afterthe relay 10 is energized to lift the lower end of the lever 12 abovethe armature 13. It will be understood, of course, that therepresentation of the relay 11 is only diagrammatic and that thearmatures 14 and 15 remained locked in their energized positions alongwith the armature 13. The switch hook springs 16, 17 and 18 are soarranged that as the switch hook rises upon the removal of the receiverthe spring 18, after disengaging the spring 19, engages the spring 16and then 'forces the spring 16 out of engagement with the spring 17. Itwill thus be seen that during the time the switch hook is rising, thereis an instant whoa the springs. 16, 17 and 18 are all in conqactat thesame time. The substation A (Fig. 2) is in all respects the same as thesubstation A except, that its switch hook con trols a simplemake-andbreak contact. The relays 20 and 21 are similar to the relays 10and 11 shown in Fig. 1, the circuit connections being somewhatdifferent, as will be pointed out hereinafter. If desired, the relay 21may be made sluggish to pull up in anyone of a: number of known manners.

The line switches C and C and the master switch are of the general typeof line and master switches disclosed in British patent to R. W. James,No. 26,301 of 1906, but of the particular form described in Britishpatent to T. G. Martin, No. 1319 of 1910.

The selectors E and F are ofthe general type of selector-switches shownin United States Letters Patent No. 815,321, granted March 13, 1906, toKeith, Erickson and Erickson, the circuits being modified, however, asshown in said British patent No.

1,419 of 1910, in order to operate in a twowire system.

The connector H is of the general type of connector switches disclosedin United States Letters Patent No. 815,176, granted 'March 13, 1906, toKeith, Erickson and Erickson, but, like the selectors, is also modiliedin order to operate in a two-wire system and being especially adapted toa partyline system.

In, order to give a complete understanding of my invention it will beexplained in general how a complete connection is established betweenthe calling substation A and the called substation A, the number ofwhich latter will be assumed to be 2220. Since the apparatus shownherein is in gen eral well known in the art and is fully described inthe publications hereinabove referred to, it is not thought necessary todescribe its construction and operation in detail herein. W hen thereceiver is removed from the switch hook at the substation A preparatoryto making a call, the switch hook 4i rises in the usual manner, and atthe instant-the spring18 engages the spring 16 and before the spring 16disengages the spring 17, the relay 11 is bridged across the lineconductors 22 and 22 whereby'a circuit is closed extending from ground Gat the central office through the springs 23 and 24, line 22 springs18,16 and 17, relay 1]., line 22, springs 25 and 26 and the line winding27 of the line switch C to the battery lead 28, thence through battery Bto ground G. 'The relay 11, upon energizing, attracts its armatures 13,14 and 15, which thereupon become locked in their operated positions, aspreviously explained. The armature 13, in its operated position,completes "a conned tion from the line conductor 22 through the relay 10to the hook switch spring 19. The armature 15, in. its operatedposition, bridges the talking circuit across the line conductors 2 2 and22. This bridge extends from the line conductor 22 through the hooksprings18 and 1G, transmitter 3, re ceiver 2, impulse springs 7 and 8,armature 15 and push button springs 29 to the conductor 22. When thetransmitter and receiver are thus bridged across the line, the currentthrough the line'winding' of the switch C 'is' increased sufiiciently tocause said winding to attract its armature 30, ii it was not already soenergized in series with the relay 11, which has considerableresistance. The armature 30, upon being attracted, 'closes thecircuitvof the operating winding 31, which causes the line switch C tooperate in the usual manner to extend the line connection through thesprings 32 and 33 and 31 and 35 to the first selector E, and the switch0 is disconnected from the line by its cut-off armature 36. Whenconnection is extended to the first selector E,-the line relay 37becomes energized by reason of the bridge across the line through thetalking circuit of the substation A and, upon energizing, closes thecircuit-of the relay 38. The relay 38. upon energizing closes a holdingcircuit for the winding 39 of the line switch C.

It will be seen that when the receiver is removed from the switching'station the talking circuit is not bridged across the line by thesimple operation of-the hook switch springs, as is usually the case, butis dependent upon the energization'of the relay 11. The relav 11 ismomentarily bridged across goes up. This relay 11 has a high resistcuitof the telephone. If no talking circuits are bridged across the line atthe time this relay is bridged across it, this relay energizes asdescribed. If, however, the line had been 15 in use by some othersubstation at the time the receiver. hook at the substation A. the relay11, when it became bridged across the line, would:

have been shunted by the talking circuit at the first substation, andthis would have shunted sufiicient current away from the relay 11 toprevent it from being opera- .tively energized and the talking circuitat the substation A would not have been bridged across the-line.

that while the line is in use at one station no subscriber at any ofthe-other stations can get in on the line. l

The connection having been extended to the first selector E by theremoval'of the re ceiver at the calling substation, I subscriber nowoperates his calling device for the first digit 2 of the called number,

whereby the substation impulse springs 7 Each time the impulse springsare separated, the line relay 37 of the selector E deeneir nizes. Eachdeenergization of the relay 37' transmits an impulse of current throughthe vertical magnet 40 of the selector. Since the digit called. is 2,the vertical magnet operates twice to raise the switch shaft and itswipers two steps, after which the side switch passes to second positionand causes the rotary magnet 41 to operate in the usual'manner to rotatethe wipers on to the contacts of anidle trunk line leading to a secondselector F. The side switch thereupon passes to third position and,throughfthe medium of its wipers 43 and 44, disconnects the line relay37 from the line circuit and extends the line connection throughtheshaft wipers 45 and 46 and the contacts upon which they have beenrotated to the second selector F. The line relay 48 of the secondselector thereupon becomes energized in the samemanner in whichthe linerelay of the first selector was energized when connection was firstextended to it.

When the substation calling device is opnumber, the selector F operatesin the same manner] as explained for the selector E inconnection'with-the previous digit to extend the connection over thetrunk conductors 49 hook at the call-- the line as the switch'hook ancecompared with that of the talking ciris again opened twice,

was removed from the .switch' It will thus be seen wipers two steps.

the calling and 8 are separated twice momentarily.

erated for the'second digit 2 of the called and 50 to. an idle connectorH which has access to the group of lines to which that of the substationA belongs and which is supplied with ringing current of the propercharacter; to operate'the ringer at thesub station A. When theconnection is thus extended to the connector H, its line relays 52. and53 become energized. Each of these relays, upon energizing, closes anenergizing v circuit' for the relay 54. a 5

When the calling subscriber operates his calling device for the thirddigit2, theline each time breaking the circuit of the" connector relays52 and 53. The relay 54, being a slow acting relay, 30 does not havetime to deenergize during the momentary interruption of its circuit by Ithe momentary denergization of the relays.

'.tact, relay 57, vertical magnet 58 and theside switchwiper 59 to thebattery lead 28;] Since the digit called is-2, the-vertical mag-- netreceives two impulses over this circuit. and operates to. raise theswitch shaft and The relay 57, which is in- I eluded in circuit in.serieswith thever tical magnet 58, is a slow acting relay and is en-'95 ergized the first impulse through it and remains energized untilafter the last impulse for the digit is delivered. .By: ener gizing anddenergizing, therela'y 57 transmits an impulse of current through theprivate magnet 60, which in turn, upon enerv gizing and deenergizmg,causes the side switch to pass from first to' second position. The sideswitch wiper 59, in passing from first to second position, teryconnection from the -vertical magnet .58 to the rotary magnet 61.Thecalling subscriber now operates his calling device for the last digit0, whereby the connector line' relay '52 is denergized ten times.Each110.

for the previous digit to cause the private 2 ma gnetto 'step the sideswitch front second to'thlrd position after, the last impulse for thelast digit 1s delivered, to the rotary magnet, 1 y 'The side switchwipers 62 and 63, upon. 125.

reaching third position, complete the connection between the calling.and the called line, as indicated by the heavy'conductorsin the drawing.The .side switchiyvipe'r 64, upon reaching third position, provides setransfers the bat through the private bank contacts ofv the called line.and an energizing circuit for the c'ut-ofl" winding 65 of theline'switch C. This guarding potential and circuit-extends from ground Gwiper 66, thence to alltheconnector private bank contacts of the calledline and also through the winding 65 to the battery lead 28. The winding65, upon energizing, at-

tracts the armature 67, whereby the line switch C is disconnected fromthe line and the contact 68 in' the talking circuit is closed. The sideswitch wiper 59 of the connector, upon reaching third position,circuitfor the ringing relay 69, which circuit extends from ground Gthrough the interrupter '70, springs 71, relay 69and the side switchwiper 59 'to the battery lead. The relay 9, upon energizing, disconnectsthe calling line from the called line and bridges the subscriber. Sincethe circuit of the ringing relay 69 includes the interrupter 70, thisrelay is energized only intermittently, so as not to ring the calledsubscriber continuously. When, the called subscriber removes hisreceiver. from the switch hook, the relay 21 is bridged across the lineby the closure of the hookswitch sp'rings'72 and 73. It Will be seenthat normally the transmitter and the receiver at thecalled station areshort-circuited through the armature 74 of the relay 21 and its backcontact. As soon as the relay 21 isthus bridged across the line, itisenergized. The relay 21, upon energizing, bridges the talking circuitacross the line through the armature 74: and its front contact andbecomes locked in its operated" position, as explained in connectionwith the relays 10 and 11 at the calling substation A. As soon as thetalking circuit at the called substation is bridged across the line, oras soon thereafter as the ringing relay 69.at theconnector denergizes,if it happens to be energized at the time, the

' called substation is provided with talking current over a circuitextending from ground G through the side switch wiper 64, lower windingof the back-bridge relay 75, thence over the heavy conductors, throughthe springs of the ringing relay, side switch wiper 63, shaft wiper 76,substation hook switch springs, 73 and 72, impulse springs 77, receiver78, transmitter 79, armature 74 and its front contact,'push button 80,contact 68, wipers 81 and 62, and the ringing relay springs, and throughthe upper winding of the back-bridge relay 7 5 to the battery lead 28.The back-br1dge relay is energized by this current, and by separatingthe springs 71 cuts off the ringing relay 69.

After the conversation is completed the entire connectionisautomatically released side switch wiper 64, shaft completes a ringingcurrent generator R across the called line to signal the called .wiper,vthence through the side by the hanging up of the receiver at the callingsubstation in the following manner: During the time the connection isbein maintained the release relays 38 and 82 of the selectors E and F,as Well as the relay 54: of the connector, are maintained energizedthrouglr the springs of the connector line relays 52 and 53. When thecalling subscriber hangs up his receiver, these relays 52 and 53deenergize and break the circuits of the relays 54:, 82 and 38 of theswitches H, F and E,-respectively. The relays 54', 82 and .38, upondeenergizing, close the circuits of their respective release magnets 83,84 and 85, which, upon energizing, release their respective switches.The relay 38 of the selector E, upon deenergizing, also-destroys theholding circuit of the Winding 39 of the line switch C and allows saidswitch to berestored to normal position. When the receiver at thecalling substation is first hung up and the springs 18 and 19 come intocontact, the -relay 10 is bridged across the line conductors 21 and 22through the armature l3 and its front contact. The relay 10 energizesand by lifting the lever 12 unlocks the armature of the relay 11 andallows it to resume its normal position. As soon as the armature 13disengages its front contact, the bridge across the line through therelay 10 is broken. At the called substation the relay 20 is energizedby the hanging up of the receiver and unlocks the relay 21in the samemanner as explainedfor the relay 10 at the calling substation.

In the foregoing it has been explained how the connector H completedconnection with an idle line. In case the called line is busy theconnector H will not complete connection therewith, and the callingsubscriber will be given a busy signal in the following manner: 1Vhenever a line is in use, either on account of having made a call or onaccount of having been called, there is a guarding ground potential uponits connector private bank contacts. Therefore, when the private Wiper66 of the connector engages the contact of a busy line, a groundpotential is extended from said contact through said switch wiper 64(which is then in second position) and through the relay springs 86 and87 and the relay 88 to the spring 89 of the private magnet relay 57.Therefore, when the private magnet relay deenergizesafter the last in1-pulse for the last digit is delivered, it does not break the circuit ofthe private magnet 60, but forms a new holding circuit for said magnetby "'ay of the relay 88 and the pri vate wiper 66. The private magnet,therefore, does not deenergize topermit the side switch to pass to thirdposition and the connection with the called'line is maintained open atthe side switch wipers 62 and 63. The relay 38, which is included in thelocktends from ground renelgllmgnshl'itsthe holding ground of itfilf andthe'irivate'magnet from the gua'rdprivatebankeontact tothegrouncl G by51.1Way;;,0f:"the-springs-87, 90 andx9l and the sidezsWitchfwi-per Theprivate magnet ..remaining:senergizedtand the side switch- -rei' mainlnglocked,;in"second pos1t1on,- the busy =signalingrmachinegcSisconnected'with the -calling-, line .through the. springs 93 of the:private magnet through the side switch i'wiper. 63;:1 (in {secondposition) thence I C It'having been shown how the connector is preventedfrom completing connection witha busy line; since a calling line isprovided wlth a guarding potential upon its connector private-bankcontacts as soon as the call 1s 1nitiated,'"some special means must heprovided in order to permit a calling subscriber to call baclg upon hisown line to. signal another subscriber thereon. This 15 "accomplished inth'e'following manner: The guarding potential which is placed upon theprivate bank contacts of the calling line ex- H G at the selector E(Fig. 1)f. through-the springs 96, thence through the: springs 97 of a.slow acting relay',' line 'switch'bank springs 98 and 99 and 'the'conductor 100 to the connector pri- 'v'atebank contacts. "The springs 97are controlled byf'a slow acting relay 101, which in turn is controlledby a. relay 102 which is inserted inoneside' of the trunk .line leadingfrom theline switch to the first selector.

' It will thus'be seen'gthat all the impulses .i'or 40 operating theswitches E, F and must pa'ssthiougli' the relay 102. Each time thisrelay deen'ergiz'es response to theseim pul e -n closesthe' circuit ofthe relay 101, this circuit extending from ground G 445 through thesprings 96- and 103' and the relay lml to the batt ery lead 28. Therelay 1 01; upon energizing'. separates the springs 97,' '",,thereby"removing the short-circuit around-[the resistance 105, whereby saidresi's'tance inc ludedlin the ground'conrlectr ats the connector privatebank contacts of the calling line; The rela 'y 101 is a slow i actingrelay .and, ;therefore remains ener- "gized'continuouslv while theimpulses are being transmitted hrough the relav102 for anvdigit. andalso]remains energized for a short time after-the last impulse for eachdigit islcompleted.. Thus it will be seen that when a calling subscriberis calling I l the time when the backonhisown line. at

private magnet. rela .57 deenergizes after a thellast di it iscalled.the resistance1-05 T wi-l-l b zinclucled in thecirciuti whlchqtencls 1to lock the private magnet 60. This resistance is high enough to.prevent saldmagnet I racemes e 60, I upon enabled in this manner talkingcircuit at the called from being locked andthe side switch passes tothird position in the 'usual fmanner and connection is thereforecompleted. A moment later the relay i 1 01 "deenergizes andshort-circuits the resistance 105, thereby restoring the guardingpotential of the lineto "its normal condition to "prevent. any'fothercon'iiector from obtaining connection therevvit When a callingsubscriber calls back on his own line, a circuit will be closed throughthe back-bridge relay" of the connector 1 through the talking circuit ofthe calling substation. This will energize the backbridge relay andprevent the ringing relay 69 from operating to signal the calledsubscriber. In order scriberin this case, the subscriber at the callingsubstation depresses the push button 29. This depressing, of the pushbutton opens a short-circuit around the relay 11 and includes said relayin the bridge across the calling line. This increases the resistance ofthe bridge sufiiciently to cause the connector back-bridge relay toallow its armature to drop back and close the circuit of the ringingrelay. The insertion of the resistance of the relay 11 in the bridgeacross the line at the calling substation also increases its resistancesufiiciently so that when the called subscriber removes his receiverthere will not be enough current shunted away from his relay 11 toprevent it from operating to complete his talking circuit. and.therefore, two subscribers are to come in on the line at the same time.Of course, when; the substation be comes bridged across the line, theconnector back-bridge relay 75 energizes again and cuts ofi the ringingcurrent. The calling subscriber then releases his push button and thetwo subscribers carry on their conversation in the usual manner.

- It will be seen that the connector H has two line relays 52 and 53,and that after the connection is completed either one or both of theserelays must be maintained energized in order to prevent the connectionfrom being released. The obiect in providing two relays is that therelay 52 must be adjusted so as to respond to the impulses for operatingthe switch. When it is thus adjusted it may possibly deenergize when thepush button at a calling station is depressed .to signal a calledsubscriber on the same line. The relay 53, however, spend toanyimpulses. may

be adjusted so that it will not be thus de'energized when the to signalthe called sub 1 not having to rethat I do not wish such system for useWith matic system, vantageously manual.

What I claim as my invention'is v 1. In a telephone system, aparty-line, a plurality of telephone stations thereon, a relay at eachof said stations, means for energizing said relay When said line istaken for use at any station, means controlled by said relay forpreventing any other subscriber from coming in on said line when saidline is busy, an electromagnet, and means controlled by saidelectromagnet for returning said relay to normal position.

2. In a telephone system, a party-line, a plurality of substationsthereon, a relay at each of said substations, means for energizing thecorresponding relay When a receiver is removed from the hook at asubstation, means for locking said relay in an energized position, meanscontrolled by the energize- .tionof said relay for preventing any othersubscriber from coming in on said line While to limit my invention to asit is equally as Well adapted any automatic or semi-autoor could even beemployed adin a system -Which is entirely the same is in use, anelectromagnet, and

meanscontrolled thereby for unlocking said rela 3. In a telephonesystem, a party line, a plurality ofsubstations thereon, a relay at eachof said substations, means for energizing the corresponding relay when areceiver is removed from the hook at a substation, means for lockingsaid relay in an energized position, means controlled by theenergizarelays upon the removal of tion of said relay for preventingany. other subscriber from coming in on said line While the same is inuse, an electromagnet, means controlled thereby for unlocking saidrelay, and means for energizing said electromagnet when the receiver isreplaced upon the hook.

4:. In a telephone system, a party-line'having a plurality ofsubstations thereon, a re lay bridged across the line at each of saidstations, means for energizing one of said 4 the correspondmg receiverfrom its book, means controlledby said relay for closing the talkingcircuit, means for preventing said relay from energizing when a receiveris removed'from the hook and said lineis busy, means for locking saidrelay in an energized positiomand anelectromagnet for unlocking saidrelay.

- 5. In a telephone system, a party-line having a plurality ofsubstations thereon, a relay bridged across the line at each of saidstations, means for energizing one of said relays-upon the removal ofthe corresponding receiver from its hook, means controlled by said relayfor closing the talking circuit, means for preventing said relay fromenergizing when a receiver is removed from the hook and said line isbusy, meansfor look ing said relay in an energized position, an

line, upon removing a receiver from its hooiz,

' plurality line While the same --net, means controlled therebyforunlocking electromagnet' forunlocking said relay, and means forenergizing said electromagnet When the receiver is replaced upon thebook.

6; In a telephone system, a party-line having a plurality of substationsthereon, a re lay at each substation bridged across said means forenergizing one of said relays means for locking said relay in anenergized position, means operated by said relay for closing a lowresistance talking bridge across said line in shunt of said relay, saidshunt preventing-any other relay being energized upon the removal of anyother subscribers receiver from the hook, an' electromagnet, meanscontrolled thereby for unlocking said relay, and means for energizingsaid electromagn'et upon replacing said receiverupon its hook. 1

7. In a telephone system, a party-line having a plurality of substationsthereon, electricallysoperated means at each of said substationsforbridging the talking circuit at its substation across the lineprovided the talking circuit is not bridged across the line at any othersubstation, and electrically-op erated means for returning said relay tonormal position.

8. In a telephone system, a party-line, a plurality of telephonestations thereon, a relay at each Of'Sitld stations, means forenergizing said relay when said useat any station;

from coming in on said line when said line is busy, an electromagnet,means controlled by said electromagnet for returning said relay tonormal position, automatic impulsetransmitting means on said line, andautomatic switches controlled. thereby.

9, In a telephone system, a party-line, a of substations thereon, arelay at each ofsaidsubstations, means for energizing thecorresponding'relay When a re ceive'r is removed from thehook at asubstation, means for locking said relayin an energized position, meanscontrolled by the energization ofSaid relay for preventing any othersubscriber from coming in on said is in use, an electromag said relay,automatic means on said line, controlled thereby. v

10. In a telephone system, a party-line, a plurality of substationsthereon, a relay at each of said substations, means "for energizing thecorresponding relay when a receiver is removed from thehook at asubimpulse-transmitting and automatic switches line is taken for, meanscontrolled 'by said relay for preventing, any other subscriber station,means for locking said relay in an M energized position, meanscontrolled by the energizatlon of sald relay for preventing any othersubscriber from coming in on said line While the same isin use, anelectromagnet, means controlled thereby for unlocking said relay, meansfor energizing said electromagnet when the receiver is replaced upon thehook, automatic impulse-transmitting means on said line, and automaticmeans controlled thereby.

11. In a telephone system, aparty-line having a plurality-of substationsthereon, a relay bridged across the line at each of said stations, meansfor energizing one of said relays upon the removal of the correspondingreceiver from its hook. means controlled by said relay for closing thetalking circuit, means for preventing said relay from energizing whenareceiver is removed from the hook and said line is busy, means forlocking said relay in an energized position, an electromagnet forunlocking said relay, automatic impulse-transmitting means on said line,and automatic switches controlled thereby.

12. In a telephone system, a party-line having a plurality ofsubstations thereon, a relay bridged across the line at each of saidstations, means for energizing one of said relays upon the removal ofthe corresponding receiver from its hook. means controlled by said relayfor closing the talking circuit, means'for preventing said relay fromenergizing when a receiver is removed from the hook and said line isbusy, means for locking'said relay in an energized position. an

electromagnetfor unlocking said relay,

. means for energizing said electromagnet when the receiver is replacedupon the hook, automatic impulse-transmitting means on said line, andautomatic switches controlled thereby.

13. In a telephone system, a partyvline having a plurality ofsubstations thereon, a

relay at each substation bridged across said line, means for energizingone of said relays upon removing a receiver from its hook, means. forlocking said relay in an. energized position, means operated by saidrelay for closing a low resistance talking bridge across said line inshunt of said. re-- lay, said shunt preventing any other. relay beingenergized upon the removal of any other subscribers receiver from thehook, an electromagnet,means controlled thereby for unlocking saidrelay, means for energizingsaid electromagnet upon-replacing saidreceiver upon its hook, automatic impulsetransmitting means on saidline, and auto-' matic switches controlled thereby.

.14. In a telephone system, a party-line having a plurality of.substations thereon,

-electrically-operated means at each of said electrically-operativemeans individual to each substation for preventing interference betweentwo subscribers, and electricallyoperat-ive means at the callingsubstation for restoring said first-mentioned means to normal position.

Si ed by me at Chicago, Cook county, Illinois, this 24th day ofFebruary, 1912'.

BERNARD D. WILLIS. Witnesses:

ARTHUR'J: RAY, ALBERT ANDERSEN.

